پيش‌بيني تغييرات آتي تبخير و تعرق پتانسيل بر اساس سناريوهاي انتشار RCP در حوزه آبخيز هليل‌رود

Predicting future changes in potential evapotranspiration based on RCP scenarios in Halilrood Watershed

ﯾﮑﯽ از اﺛﺮات ﺗﻐﯿﯿﺮات اﻗﻠﯿﻤﯽ در دﻫﻪ ﻫﺎي اﺧﯿﺮ، ﺗﻐﯿﯿﺮات ﭼﺮﺧﻪ ﻫﺎي آﺑﯽ در ﻣﻨﺎﻃﻖ ﻣﺨﺘﻠﻒ زﻣﯿﻦ ﺑﻮده اﺳﺖ. ﺗﺒﺨﯿﺮ و ﺗﻌﺮق ﻧﯿﺰ ﺑﻪ ﻋﻨﻮان ﯾﮑﯽ از ﺑﺨﺶ ﻫﺎي ﭼﺮﺧﻪ ﻫﯿﺪروﻟﻮژي، دﺳﺘﺨﻮش اﯾﻦ ﺗﻐﯿﯿﺮات ﺧﻮاﻫﺪ ﺑﻮد. ﻟﺬا، در ﭘﮋوﻫﺶ ﺣﺎﺿﺮ، اﺛﺮ ﺗﻐﯿﯿﺮ اﻗﻠﯿﻢ ﺑﺮ ﺗﻐﯿﯿﺮات ﺗﺒﺨﯿﺮ و ﺗﻌﺮق ﭘﺘﺎﻧﺴﯿﻞ در ﺣﻮزه آﺑﺨﯿﺰ ﻫﻠﯿﻞ رود، ﺗﺤﺖ ﺳﻨﺎرﯾﻮﻫﺎي RCP 4.5 ،RCP2.6 و RCP 8.5 ﺑﺎ اﺳﺘﻔﺎده از ﻣﺪل رﯾﺰﻣﻘﯿﺎس ﻧﻤﺎﯾﯽ LARS-WG و ﺧﺮوﺟﯽ ﻣﺪل ﮔﺮدش ﻋﻤﻮﻣﯽ HadGEM2 در دوره زﻣﺎﻧﯽ آﺗﯽ )2021-2040( ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮار ﮔﺮﻓﺖ و ﺑﺎ اﺳﺘﻔﺎده از ﭘﺎراﻣﺘﺮﻫﺎي اﻗﻠﯿﻤﯽ ﭘﯿﺶ ﺑﯿﻨﯽ ﺷﺪه، ﻣﯿﺰان ﺗﺒﺨﯿﺮ و ﺗﻌﺮق در ﺳﻄﺢ ﺣﻮﺿﻪ ﺑﺎ اﺳﺘﻔﺎده از روش ﺗﻮرﻧﺖ واﯾﺖ ﺑﺮاي دوره آﺗﯽ ﻣﺤﺎﺳﺒﻪ ﺷﺪ. ﺑﺮ ﻃﺒﻖ ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ از ﻣﺪل LARS-WG در ﺳﻄﺢ ﺣﻮﺿﻪ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ، ﻣﯿﺰان ﺑﺎرش در دوره آﺗﯽ ﻧﺴﺒﺖ ﺑﻪ دوره ﭘﺎﯾﻪ ﮐﺎﻫﺶ و ﻣﯿﺰان دﻣﺎ ﺗﺤﺖ ﺗﻤﺎﻣﯽ ﺳﻨﺎرﯾﻮﻫﺎ اﻓﺰاﯾﺶ ﺧﻮاﻫﺪ ﯾﺎﻓﺖ. ﻣﯿﺰان ﺗﺒﺨﯿﺮ و ﺗﻌﺮق ﻧﯿﺰ ﺑﺮ اﺳﺎس وﺿﻌﯿﺖ دﻣﺎ و ﺑﺎرش ﭘﯿﺶ ﺑﯿﻨﯽ ﺷﺪه اﻓﺰاﯾﺶ ﺧﻮاﻫﺪ ﯾﺎﻓﺖ. ﺑﻪ ﻃﻮري ﮐﻪ ﻧﺘﺎﯾﺞ ﺑﺮرﺳﯽ وﺿﻌﯿﺖ ﺗﺒﺨﯿﺮ و ﺗﻌﺮق در ﺳﻄﺢ ﺣﻮﺿﻪ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﺣﺎﮐﯽ از اﻓﺰاﯾﺶ ﻣﯿﺰان ﺗﺒﺨﯿﺮ و ﺗﻌﺮق در دوره آﺗﯽ )2021-2040( ﻧﺴﺒﺖ ﺑﻪ دوره ﭘﺎﯾﻪ ﻣﯽ ﺑﺎﺷﺪ ﮐﻪ اﯾﻦ ﻣﯿﺰان ﺑﻪ ﻃﻮر ﻣﺘﻮﺳﻂ در دﻫﻪ آﺗﯽ ﺑﻪ ﻣﯿﺰان 6/8 ،3/4 و 8/5 درﺻﺪ ﺑﻪ ﺗﺮﺗﯿﺐ ﺗﺤﺖ ﺳﻨﺎرﯾﻮﻫﺎي 2.6 RCP 4.5 ،RCP و 8.5 RCP ﺧﻮاﻫﺪ ﺑﻮد. ﺑﺮ ﻃﺒﻖ ﻧﺘﺎﯾﺞ، ﺑﯿﺸﺘﺮﯾﻦ اﻓﺰاﯾﺶ دﻣﺎ و ﺗﺒﺨﯿﺮ و ﺗﻌﺮق و ﺑﯿﺸﺘﺮﯾﻦ ﮐﺎﻫﺶ ﺑﺎرش در ﺳﻄﺢ ﺣﻮﺿﻪ ﻣﺮﺑﻮط ﺑﻪ ﺳﻨﺎرﯾﻮي 8.5 RCP ﻣﯽ ﺑﺎﺷﺪ. از ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ از اﯾﻦ ﭘﮋوﻫﺶ ﻣﯽ ﺗﻮان در ﻣﻄﺎﻟﻌﺎت ﻣﺮﺑﻮط ﺑﻪ ﻣﺪﯾﺮﯾﺖ ﻣﻨﺎﺑﻊ آب، ﻣﻄﺎﻟﻌﺎت ﮐﺸﺎورزي و زﯾﺴﺖ ﻣﺤﯿﻄﯽ اﺳﺘﻔﺎده ﻧﻤﻮد.

Changes in water cycles in different parts of the world is one of the effects of climate change in recent decades. Evapotranspiration, as the part of the hydrological cycle, will also undergo these changes. Therefore, in the present study, the effect of climate change on potential evapotranspiration changes in Halilrood Watershed, under RCP2.6, RCP 4.5 and RCP 8.5 scenarios using LARS-WG downscaling model and the output of the general circulation model of HadGEM2 in future (2021-2040) was studied and the rate of evapotranspiration at the basin scale was calculated based on the predicted climatic parameters using Tornthwaite method in future. According to the results of the LARS-WG model, in the study area, precipitation will decrease and the temperature will increase under all scenarios in future compared to the baseline period. Evapotranspiration will also increase based on the predicted temperature and precipitation. So that, at the basin scale, evapotranspiration will increase by 3.4, 6.8 and 8.5 under RCP 2.6, RCP 4.5 and RCP 8.5 scenarios in future (2040-2021), respectively. According to the results, the highest increase in temperature and evapotranspiration and the highest decrease in precipitation at the basin scale is related to the RCP 8.5 scenario. The results of this study can be used in studies related to water resources management, agricultural and environmental studies.